Let's make a felt bracelet with LEDs!
I like to make felt, and I also like to play with electronics, so I decided to put them together and make something that is fashionable and geeky at the same time. In this Instructable, I used felt that I made myself, using a wet-felting process for the base, and needle-felting for the designs. You can learn more about wet felting by visiting my site, "The Art and Science of Felting". There are many needle felting websites, too.
Let's get started!
Step 1: Materials
You will need:
- 2 Felt strips at least 10 inches long by about 2 inches wide (or wider if you like). The felt needs to be able to go around your wrist and have extra to overlap and cover the rough electronics parts. You could also use fabric for this project, but it needs to be thick and sturdy.
- 5mm LEDs or 3mm LEDs - I get mine on eBay
- Plastic LED holders (Optional) like THESE
- Weldbond Glue or hot glue
- Embroidery floss or thread to sew pieces together
- CR 2032 Coin Cell Battery
- Sewable Coin Cell Battery Holder (From SparkFun or make your own)
- Snaps or velcro to use as a closure
- Conductive thread (I get mine from SparkFun)
Step 2: Attach LEDs and Draw "Traces"
- Decide where you will place your LEDs and punch holes large enough to fit the LED and the holder.
- Attach the LED holder to the LED and mark the cathode (negative, shorter) leg with a black marker. This helps you keep track of the negative and positive legs of the LEDs. It is very important to keep track of the polarity of each LED leg. Place each LED and its holder in place through the hole.
- On the underside, using needle-nose pliers, curve the legs into loops for sewing. They need to be large enough to fit a needle. Twist them a bit so they lay flat on the felt.
- Arrange the LEDs so the anodes (positive legs) are all on one side and the cathodes (negative legs) are all on the other side, as shown in the picture. The LEDs will not illuminate if you "cross" or short-circuit the conductive thread, so be sure you are very careful with this step.
- With marker, draw a + and - at the top of the piece of felt, corresponding with the orientation of the anodes and cathodes. Then draw your "traces" - a path linking all the anodes (positive legs), and a second, separate path for all the cathodes (negative legs). See picture.
Step 3: Sewing Your "Traces" and Battery Holder.
On this example, the negative side is on the right, and the positive side is on the left.
- Thread your needle with about 16" of conductive thread and knot the end. See THIS INSTRUCTABLE if you need to brush up on your embroidery skills.
- Beginning at the bottom (either the positive or negative side), attach the LED "loop" by sewing around it three or four times. Make sure you are pulling the thread taut, making a strong connection to the LED loop.
- Continue with a running stitch to the next LED, following the dotted line you drew in the last step.
- Repeat the process for each LED on this side, ending at the top, where you drew your + or -.
- Remove the needle from the thread, leaving a "tail". You will use this thread later for the battery holder.
- Repeat the process for the other side starting with a new 16" piece of conductive thread. It's important that you use a separate piece of conductive thread for each side. You want the positive side to connect to the positive side of the battery, and the negative side to connect to the negative side of the battery.
- Turn the felt so the right side is facing up and position your battery holder with the + and - sides of the holder corresponding to the orientation of how you placed the anodes and cathodes on the other side. Bringing one thread to the other side, sew the battery holder in place with three or four stitches through the + (or - , depending on which thread you started). Poke your needle to the back of the bracelet and tie a knot. Sew a few running stitches to the second + or - pin, poke the needle back to the other (right) side and sew around the second pin three or four times. Now poke the needle to the back of the bracelet, and tie off. Snip the thread close to the knot. It's important to keep all conductive threads taut. If they are loose, there is a greater chance for a short-circuit, and that would make you sad.
Step 4: Switch on the Power and Finish Bracelet
Ready for the "Ta Da!" moment?
- Insert the battery and slide the switch to "ON"
- Ta Da! (If you don't have a "Ta Da" moment, see troubleshooting tips in the next step).
- Once you are sure everything is working, place some hot glue around the LEDs (on the back side) and on the knots you tied. This ensures that everything will stay put during normal wear and tear.
- Before the hot glue solidifies, place a small square of thin felt over the LED area, pressing on it to adhere the hot glue. This is a second measure to make sure the negative and positive lines touch the opposing line, causing a short circuit.
- Place your second piece of felt over the back (rough) side of the bracelet and sew it in place. The Button Hole Stitch works well here, but you could use a running stitch, or even some hot glue, if you don't want to do any more hand sewing than you have to.
- Sew on the snaps as shown. Two (female) sides of the snaps are sewn on the right side, next to the battery as shown in the third picture. Using your own wrist as a guide to determine placement, sew the two remaining snaps to the wrong side of the bracelet.
- Wear proudly! It also makes a great gift.
Step 5: Troubleshooting and Taking It Further
If you did not have a "Ta Da" moment and the lights did not illuminate, there are some things you can do.
- Check to make sure the LEDs are oriented correctly. If you colored the cathode (negative) leg with the marker, you should be able to see the black color on the loop you created with the needle nose pliers. Make sure that all the negative 'nodes are on the one side and the positive 'nodes on the other. If one is wrong, just snip the threads around the loops and twist the LED so it is correct. With a new piece of conductive thread, connect the LED to the appropriate trace line and fasten off. Use a separate piece of thread for the other let.
- A great tutorial on sewing with Conductive Thread is on SparkFun, it shows some additional information about short-circuits. They use their sewable LEDs, which are fun, but the "regular" LEDs work the same way.
- When using regular LEDs, try to use all of the same color in your project. Each color of LED uses up a certain amount of power, and the color that uses the most power, "wins" and the remaining colors are left blank. There's math behind the reasons why this is so, and I won't go into it here. My best idea for a "work-around" is to either stick to one color for the whole project or, combine only the "warm" colors (red, yellow, orange) or only the "cool" colors (blue, white, green). However check your green LED. Sometimes it works with all colors, but test to be certain.
- If your lights flicker rather than shine brightly, it may mean that you have some stray conductive thread fibers flying around, causing short circuits. Make sure all of your snipped away scraps of conductive thread are removed from your project. It's amazing how conductive that stuff is when you don't want it to be. Ask me how I know!
- Check your battery and make sure the positive side is facing UP. These little batteries will last a long time if you remember to switch it OFF when you don't need the lights. If left unattended, the battery will drain completely within about 24 hours. I like to keep a supply of these batteries on hand in case one starts showing its age. You can stock up on these for a very reasonable price on eBay, or you can pay 3 or 4 bucks for one from a brick-and-mortar type store.
Taking it further:
- An illuminated bracelet can also be a nice safety accessory when walking at night. Wear it the next time you take a walk. You will be seen for sure.
- Some people have told me that these bracelets would be nice to wear while "out on the town." Definitely would get you noticed, or at least be a good ice breaker for a conversation with someone.
- You can put LEDs on any wearable - a hat, necklace, or scarf, just as long as you have a way to hide the battery holder or make it part of the design and still be comfortable to wear.
- Other ideas? Leave your suggestions below!